1. Field of the Invention
This invention relates to aqueous titanium dioxide dispersions containing alkyl polyglycosides as the dispersant.
2. Description of the Related Art
Titanium dioxide is commonly used as a pigment in oil-based and water-based paints. Titanium dioxide is incorporated as an aqueous dispersion into water-based latex paints which normally contain at least titanium dioxide, water, and a polymer latex which is a dispersion of polymer particles. However, a number of problems have been associated with the use of aqueous TiO.sub.2 slurries. For example, slurries which contain large amounts of TiO.sub.2 and no dispersant exhibit unacceptably high viscosities. In the formulation of water-based paints containing TiO.sub.2 it has been observed that individual TiO.sub.2 particles tend to agglomerate and form clumps which settle and are difficult to redisperse. As a result, water-based paints containing TiO.sub.2 pigments exhibit a storage stability problem in that the pigment particles tend to settle out over time. To overcome these problems, dispersing agents are normally added to the paint formulations. The most common dispersing agents are low molecular weight polyacrylic acids. Polyacrylic acids suffer from the disadvantages that they always contain some residual acrylic acid monomer which presents a health and safety hazard to the manufacturers and end users of the water-based paints. Another drawback associated with the use of polyacrylic acids as dispersants is that these compounds are most effective in the neutralized salt form. This limits their applications to alkaline pH systems and can create moisture sensitivity problems in the finished coating.